Statistics 3022

So, we should reject the null hypothesis H0. At a 0.05 level of significance level, we conclude that there is a significant difference between the average height for females and the average height for the males.

Rockwell, the shuttle’s primary contractor, did not support the launch due to the possibility of ice leaving the structure and damaging the thermal shield tiles during takeoff. Their concerns were relayed to NASA, but in such a way that NASA chose to proceed with the launch [2]. Though this was eventually determined to be a non-issue in the Challenger launch, the true nature of the problems that can occur when an object strikes the shuttle during takeoff would not be learned until 2003, when the space shuttle Columbia disintegrated on re-entry due to damage of a heat shield tile that occurred during takeoff [2]--[3].

Assume 20% of all email is spam. A large Internet provider plans on conducting a survey of 900 emails to see what percentage are spam.

Consider the following scenario in answering questions 5 through 7. In an article appearing in Today’s Health a writer states that the average number of calories in a serving of popcorn is 75. To determine if the average number of calories in a serving of popcorn is different from 75, a nutritionist selected a random sample of 20 servings of popcorn and computed the sample mean number of calories per serving to be 78 with a sample standard deviation of 7.

3. Questions 3a through 3d are based on a distribution of scores with and the standard Draw a small picture to help you see what is required.

The t-test is a parametric analysis technique used to determine significant differences between the scores obtained from two groups. The t-test uses the standard deviation to estimate the standard error of the sampling distribution and examines the differences between the means of the two groups. Since the t-test is considered fairly easy to calculate, researchers often use it in determining differences between two groups. When interpreting the results of t-tests, the larger the calculated t ratio, in absolute value, the greater the difference between the two groups. The significance of a t ratio can be determined by comparison with the critical values in a

c) What is the null and alternative hypothesis? Do the data results lead you to reject or fail to reject the null hypothesis?

The null hypothesis was that the female and male shoe sizes have an equal mean while the alternative hypothesis was that female and male shoe sizes do not have an equal mean. With the degrees of freedom being 33, the t-statistic is -8.27. The probability that -8.27 is ≤-1.69 is 7.5×10-10 for the one-tailed test. Also, the probability that -8.27 is ≤ ±2.03. is 1.5×10-9 for the two-tailed test. Due to both probabilities being under the alpha value of 0.05, the null hypothesis is rejected, and the alternative hypothesis is accepted at the 95% confidence level.

Read the directions and write answers independently. 1. (L.2) Choose the sentence with correct capitalization and punctuation. A. Mrs. Brown catches the bus at the corner of Elm and N. Grove.

The alternative hypothesis is Ha: μ>3200; therefore, the given test is a one-tailed (upper-tailed) z-test.

1. Write a null and an alternative hypothesis for each of the following. Be sure to state

1. Identify each of the unknown samples(use specific data to justify your answers for A and B).

B) A test statistic of t = 1.813 with d.f. = 15 leads to a clear-cut decision.

A pharmaceutical company is testing the effectiveness of a new drug for lowering cholesterol. As part of this trial, they wish to determine whether there is a difference between the effectiveness for women and for men. Using   = .05, what is the value the test statistic?

One of the greatest tragedies in history occurred on January 8, 1986. Shortly after it was launched, the space shuttle Challenger exploded, killing seven astronauts, including Christa McAuliffe, a New Hampshire schoolteacher chosen to be the first teacher in space (“Challenger Disaster, n.d.). The explosion was caused by a failure of the O-rings of the solid rocket boosters. The O-rings were unable to seat properly, causing the leaking of hot combustion gases, which burnt through the external fuel tank. The malfunction was not any one person’s or organization’s fault; it was caused by many factors including the decision to launch despite the cold weather, the poor communication between management levels of the National Aeronautics and